Disclosed herein are devices, systems and methods of stabilization of the bony elements of the skeleton. These devices will permit adjustment and maintenance of the spatial relationship(s) between neighboring bones. Depending on the specifics of the design, the motion between skeletal segments may be immobilized completely or preserved.
Surgical reconstructions of the bony skeleton are common procedures in current medical practice. Regardless of the anatomical region or the specifics of the reconstructive procedure, many surgeons employ an implantable device that can adjust, align and maintain the spatial relationship(s) between adjacent bones.
Whether from degenerative disease, traumatic disruption, infection or neoplastic invasion, alteration in the anatomical relationships between the spinal vertebras can cause significant pain, deformity and disability. Spinal disease is a major health problem in the industrialized world and the surgical treatment of spinal pathology is an evolving discipline. The current surgical treatment of abnormal vertebral motion is the complete immobilization and bony fusion of the involved spinal segment. An extensive array of surgical techniques and implantable devices have been formulated to accomplish this goal.
Vertebral fusion may be accomplished by using an anterior, lateral or posterior approach and each has particular advantages and draw backs. Frequently, circumferential fusion of the unstable level with fixation of both the anterior and posterior aspect of the spine is desired. This requires that patients undergo a combination of the aforementioned approaches. The anterior or lateral approaches are used to insert the bone graft into the disc space between the adjacent vertebras while the posterior approach is used to place bone screws or similar fasteners that are used to immobilize the vertebral bodies.
A Trans-foraminal Lumbar Interbody Fusion (TLIF) is known in the art to permit circumferential fusion of the spine through a single surgical approach. (The procedure is described in several literature citations, including: Transforaminal Lumbar Interbody Fusion by Alan Moskowitz, Orthop Clin N Am 33 (2002) 359-366. The article is hereby incorporated by reference in its entirety.)
The procedure requires an oblique approach to the posterior aspect of the spine. Unfortunately, an oblique operative corridor is less familiar to surgeons and contains fewer recognizable anatomical landmarks—leading to a higher rate of intra-operative confusion and loss of direction among operating surgeons. This difficulty is compounded when the procedure is performed using minimally invasive or percutaneous surgical technique, wherein the extent of tissue exposure is purposefully minimized. With the lack of surgical landmarks, the probability of intra-operative misdirection and the consequent development of surgical complications are necessarily increased.
In the current execution of the trans-foraminal lumbar interbody fusion (TLIF), the surgeon makes a skin incision posterior to the spinal level that is to be fused, develops a dissection corridor through the soft tissues adjacent to the spine and arrives at a facet joint of the spinal level to be fused. The facet joint is then at least partially removed in order to provide access to the posterior surface of the disc space which is positioned immediately anterior to the facet joint. The disc space is entered, prepared to accept fusion (preparation of the disc space is a well known procedure in the art and will not be described in detail here) and then implanted with the desired implant and material. After disc space implantation, the surgeon frequently, but not necessarily, desires to add supplemental orthopedic instrumentation to rigidly fixate the operative level while the bony fusion matures. Most commonly, the supplemental fixation involves placement of bone anchors (usually screws) that are interconnected with an interconnecting members (usually one or more rods).
In the current execution of the trans-foraminal lumbar interbody fusion (TLIF), it is the development of a dissection corridor through the soft tissues from the skin incision to the facet joint that is most likely to create disorientation and confusion. The surgeon often arrives at a bony prominence of the underlying vertebral bones but may be unclear as to which segment of the bone it is or the precise orientation of the soft tissue corridor relative to the vertebral bones that must be fused. The lack of reliable surgical landmarks during development of the oblique soft tissue corridor adds to the uncertainly and this difficulty is compounded when the procedure is performed using minimally invasive or percutaneous surgical technique, wherein the extent of tissue exposure is purposefully minimized.